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WASHINGTON — Al-Qaida is in decline around the world but is still a leading threat to the United States, the top U.S. intelligence official said Tuesday in an annual report to Congress on threats facing the country.

Director of National Intelligence Jim Clapper also told the Senate Intelligence Committee that Iran's leaders seem prepared to attack U.S. interests overseas, particularly if they feel threatened by possible U.S. action.

The U. S. now faces many interconnected enemies, including terrorists, criminals and foreign powers, who may try to strike via nuclear weapons or cyberspace, with the movement's Yemeni offshoot and "lone wolf" terror attacks posing key threats, he said.

But while al-Qaida still aspires to strike the U.S., it will likely have to go for "smaller, simpler attacks" as its ranks are thinned by continued pressure from U.S. drone strikes and special operations raids since Osama bin Laden's death at the hands of Navy SEALs in Pakistan last year.

"We judge that al-Qaida's losses are so substantial and its operating environment so restricted that a new group of leaders, even if they could be found, would have difficulty integrating into the organization and compensating for mounting losses," Clapper said.

The intelligence community predicts that al-Qaida's regional affiliates - from the Yemeni offshoot al-Qaida in the Arabian Peninsula to Somalia's al-Shabaab - will "surpass the remnants of core al-Qaida in Pakistan," and try to attack "Western targets in its operating area." The Yemeni branch of al-Qaida remains the most likely affiliate to try to attack the U.S. homeland, he added.

The U.S. continues to put pressure on the Yemeni offshoot, and on Monday mounted airstrikes targeting al-Qaida leaders there, killing at least four suspected militants, according to Yemeni and military officials.

Just below al-Qaida on the list of threats comes the possibility of proliferation of weapons of mass destruction, from chemical and biological, to nuclear and radiological. The intelligence community does not believe states that possess them have supplied them to terror groups, but that remains a risk.

'Keeping open the option'
Iran has the technical ability to build a nuclear weapon, but simply hasn't decided to yet, Clapper said.

"We assess Iran is keeping open the option to develop nuclear weapons, in part by developing various nuclear capabilities that better position it to produce such weapons," Clapper said.

Citing last year's thwarted Iranian plot to kill the Saudi ambassador in the U.S., "some Iranian officials - probably including Supreme Leader Ali Khamenei ... are now more willing to conduct an attack in the United States in response to real or perceived U.S. actions that threaten the regime," Clapper said.

The North Korean nuclear weapons program is a continued threat to global security, though the program is intended for self-defense, his assessment states: "We judge that North Korea would consider using nuclear weapons only under narrow circumstances" and "probably would not attempt to use nuclear weapons against U.S. forces or territory, unless it perceived its regime to be on the verge of military defeat and risked an irretrievable loss of control."

China and Russia remain the key threats to the U.S. in cyber-space, with "entities" in both countries "responsible for extensive illicit intrusions into US computer networks and theft of US intellectual property," though Iran is also a player, Clapper said.

He warned of growing cyber-espionage by foreign governments against U.S. government and businesses, and said many such intrusions are not being detected.

Insider threats are another category of risk, in which disgruntled employees like accused Army soldier Bradley Manning allegedly leak information to the public or sell it to competing corporations or nations.

The annual threat assessment looked further afield to places like Afghanistan, where it assessed the Afghan government's progress as fragile, and the Taliban as "resilient." The group is less able to intimidate the Afghan population that last year, especially in areas where NATO forces are concentrated, but its leaders continue to direct the insurgency from their safe haven in Pakistan, the report said.

The continent of Africa got one of the grimmest reviews. Africa remains "vulnerable to political crises, democratic backsliding, and natural disasters." Violence, corruption and terrorism are likely to plague Africa in areas key to U.S. interests, the review said, with unresolved discord between Sudan and South Sudan, continued fighting in Somalia, and extremist attacks in Nigeria.

Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Video: Report: Iran willing to attack inside US

Closed captioning of: Report: Iran willing to attack inside US

>>u.s. intelligence
showing increasing concern today that the nuclear threat is only part of the real threat that tehran maying embracing plots to attack american assets around the world. we have bruce with us. let's take it point by point, because we had all the intelligence officials testifying their semiannual threat assessment to the
senate intelligence committee
today. first of all,
iran
and the nuclear threat and what
israel
may or may not be doing. what is your sense from everything that you have gleaned from officials about where
israel
is and why we are hearing so much noise from
israel
and forces about the polli ipossibility of
military action
.

>>i think that there are some that fear the window of opportunity to do something about
iran's nuclear program
is getting
smaller and smaller
and the time for action, if there's to be
military action
, is getting shorter and shorter. the
u.s. intelligence
committee's assessment argued that the real question in
iran
today is whether tehran has the political will to make a bomb. not whether it has the technical capability to do so. most of the technical capability is in place there already. so it's a question of will and that puts more pressure on
israel
to make its mind up about what it's going to do about
iran
passing the nuclear threshold.

>>and would
israel
, first of all, act without the
united states
?

>>well, we have a long history, the
israel military
activities and in very, very few cases has
israel
come to the
united states
ahead of time and asked for permission to act. the number of cases where
israel
has decided to go on its own are much higher than that, against iraq in
1981
and against the palestinians this many occasions and against lebanon in
2006
. we are close allies and they will listen to the
united states
. if they get a no don't do it, that is something that they would have to think about long and carefully. if they get anything else, i see
israel
will probably make its own decision and calculate that the
united states
will come along afterwards.

>>general petraious was asked what our
red line
is.

>>if there's a decision to enrich beyond the 20% that they are currently enriching to, to the
weapons grade
, that would be very significant. there's no commercial use for that. argue ably, in fact not arguably, in fact the amount of 20% enriched uranium that they have exceeds any need for the reactor for the foreseeable future.

>>which is making your point. that they now have the capability to do almost anything that they want. the leap from 20% enrichment to 90% enrichment is not a
big deal
technologically.
israel
and the u.s. most likely or some combination have covertly slowed them down. we have seen five scientists assassinated and the
computer virus
, it seems from my reporting and you are saying, that
israel
is getting close to a decision that you cannot really accomplish that covertly and for the prime minister and for the
defense minister
, the former prime minister, this is a threat. the other thing that petraious said and senator feinstein said that they met with the leader, and they met with the ma saud leader, they are getting the
direct line
from
israel
that this thing is heating up

>>the
israel
government is clearly very worried. but it's important to note that there's a heated debate within
israel
, there's former senior
government officials
, including the last three heads, have all said that they think
military action
against
iran
is a mistake and that it will be more counter productive than productive. and that
israel
does not face a threat from the iranian nuclear problem, it faces a serious threat but
israel
has the means to protect itself. one of the things you the did not hear the american
intelligence community
talk about today because it never does is
israel
's
nuclear deterrent
which is quite formidable.

>>even though there's debate,
israel
public opinion is divided 50/50, the fact is that the leaders are ina agreement on the harder line on this. one more thing, the retaliation that
iran
would take against the u.s., it u.s. assets and what was said today that
iran
will take action on u.s. soil, they are coming to that action, and other plots were foiled and there could be attacks against u.s. interests in the
united states
?

>>in fact, the
united states
is far more vulnerable than
israel
,
israel
is relatively small. getting at
israel
is hard to do and it has formidable defenses for it. america has assets and vulnerablities around the world. here at home, we saw an plot to set up a bomb in washington. in the
middle east
, through 90,000
american soldiers
in afghanistan, immediately next to
iran
.
iran
could heat up the
war in afghanistan
quickly and make obama's war there very, very difficult to succeed in if it chose to counter an american
israel
attack on
iran
by going after our softer, vulnerable places.